System and method for monitoring occupancy of a building using a CO2 concentration monitoring device

Patent metadata

Field	Value
Publication number	US-12031965-B2
Application number	US-201816222561-A
Country	US
Kind code	B2
Filing date	Dec 17, 2018
Priority date	Feb 25, 2015
Publication date	Jul 9, 2024
Grant date	Jul 9, 2024

Abstract

A building loses or gains heat through its envelope based on the differential between the indoor and outdoor temperatures. The losses or gains are due to conduction and infiltration. Conventionally, these effects are typically estimated by performing an on-site energy audit. However, total thermal conductivity, conduction, and infiltration can be determined empirically. The number of air changes per hour are empirically measured using a CO2 concentration monitoring device, which enables the infiltration component of total thermal conductivity to be measured directly. The conduction component of thermal conductivity can then be determined by subtracting the infiltration component from the building's total thermal conductivity.

First claim

What is claimed is:

1. A system for monitoring occupancy of a building using a CO 2 concentration monitoring device, comprising:
a plurality of CO 2 concentration monitoring devices interfaced to a computer processor and provided inside a building under test and operable to determine and record a plurality of CO 2 concentrations, wherein at least some of the CO 2 concentration monitoring devices are in a different location in the building than at least one other of the CO 2 concentration monitoring devices;
a storage on which a baseline CO 2 concentration applicable to outside the building and a total thermal conductivity of the building are recorded;
the computer processor interfaced to the storage and configured to execute code, the computer processor configured to:
receive one or more of the CO 2 concentrations recorded by the plurality of the CO 2 concentration monitoring devices at a same time, compare at least one of the received CO 2 concentrations to another one of the received CO 2 concentrations to determine how well CO 2 mixes throughout the building, and determine a quantity of the CO 2 concentration monitoring devices comprised in the plurality for use in the test based on the CO 2 mixing determination;
set one of the concentrations of the CO 2 concentrations recorded by each of the CO 2 concentration monitoring devices comprised in the quantity before an increase in CO 2 concentration level in the building as an initial CO 2 concentration associated with that CO 2 concentration monitoring device, wherein the increase in the CO 2 concentration level is due to a CO 2 source inside the building, the CO 2 source comprising one of dry ice being converted from solid to gaseous form and a discharge of a CO 2 fire extinguisher in the building;
from each of the CO 2 concentration monitoring devices comprised in the quantity receive further ones of the CO 2 concentrations inside the building subsequent to the increase in CO 2 concentration level and a negation of inside the building until the further CO 2 concentrations stabilize, wherein the stabilization comprises at least one of one of the further CO 2 concentrations equaling the baseline CO 2 concentration and a plurality of the further CO 2 concentrations being the same;

from one or more of the CO 2 concentration monitoring devices comprised in the quantity receive additional ones of the CO 2 concentrations following the stabilization;
for each of the CO 2 concentration monitoring devices comprised in the quantity, determine a number of air changes in the building using the initial CO 2 concentration recorded by that CO 2 concentration monitoring device, the baseline CO 2 concentration, and at least one of the further CO 2 recorded by that CO 2 concentration monitoring device at the stabilization;
determine infiltration of the building based on the number of air changes associated with at least one of the CO 2 concentration monitoring devices comprised in the quantity;
determine conduction of the building as the difference of the total thermal conductivity less the infiltration of the building; and
monitor occupancy of the building based on the determined infiltration and based one or more of the additional CO 2 concentrations.

2. A system according to claim 1 , further comprising:
a further CO 2 concentration monitoring device checked against one of the CO 2 concentration monitoring devices and configured to measure the baseline CO 2 concentration applicable to outside the building.

3. A system according to claim 1 , wherein a time from the beginning of the negation to the stabilization is one hour.

4. A system according to claim 1 , wherein the computer processor is remotely interfaced to the CO 2 concentration monitoring devices.

5. A system according to claim 4 , wherein a mobile phone comprises the computer processor.

6. A system according to claim 1 , wherein the number of air changes n for each of the CO 2 concentration monitoring devices comprised in the quantity is determined in accordance with:

n
=

ln
⁡
(

C
0
Inside

-

C
Outside

C
t
Inside

-

C
Outside

)

⁢

(

1
t

)

where C 0 inside is the initial CO 2 concentration; C t Inside is the further CO 2 concentration at time t;
C Outside is the baseline CO 2 concentration; and t is time expressed in hours.

7. A system according to claim 1 , the computer processor further configured to:
determine the infiltration of the building based on the number of air changes associated with at least one of the CO 2 concentration monitoring devices comprised in the quantity as a function of steady-state, fully-occupied conditions inside the building.

8. A system for controlling ventilation of a building through using a CO 2 concentration monitoring device, comprising:
a plurality of CO 2 concentration monitoring devices interfaced to a computer processor and provided inside a building under test and operable to determine and record a plurality of CO 2 concentrations, wherein at least some of the CO 2 concentration monitoring devices are in a different location in the building than at least one other of the CO 2 concentration monitoring devices;
a storage on which a baseline CO 2 concentration applicable to outside the building and a total thermal conductivity of the building are recorded;
the computer processor interfaced to the storage and configured to execute code, the computer processor configured to:
receive one or more of the CO 2 concentrations recorded by the plurality of the CO 2 concentration monitoring devices at a same time, compare at least one of the received CO 2 concentrations to another one of the received CO 2 concentrations to determine how well CO 2 mixes throughout the building, determine a quantity of the CO 2 concentration monitoring devices comprised in the plurality for use in the test based on the CO 2 mixing determination;
set one of the concentrations of the CO 2 concentrations recorded by each of the CO 2 concentration monitoring devices comprised in the quantity before an increase in CO 2 concentration level in the building as an initial CO 2 concentration associated with that CO 2 concentration monitoring device, wherein the increase in the CO 2 concentration level is due to a CO 2 source inside the building, the CO 2 source comprising one of dry ice being converted from solid to gaseous form and a discharge of a CO 2 fire extinguisher in the building;
from each of the CO 2 concentration monitoring devices comprised in the quantity receive further ones of the CO 2 concentrations inside the building subsequent to the increase in CO 2 concentration level and a negation of insi

Assignees

• Clean Power Res L L C

Inventors

• Hoff Thomas E

Classifications

• G06F17/18

  for evaluating statistical data {, e.g. average values, frequency distributions, probability functions, regression analysis (forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04)} · CPC title

• G06F2111/10

  Numerical modelling · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• G01N33/0075

  for multiple spatially distributed sensors, e.g. for environmental monitoring · CPC title

• G01N33/0062

  concerning the measuring method or the display, e.g. intermittent measurement or digital display · CPC title